The yields of such dihydroxycarbonyl products have been measured to increase continuously from 0.04 for 1-butene to 0.6 for the 1-octene reaction (Kwok et al., 1996b). The low yield for f-butene reflects the fact that only one of the two possible alkoxy radicals formed can undergo isomerization via a 6-membered transition state.

The carbon-centered hydroxy-containing radical CH2OH formed in reactions (37) and (39) is encountered frequently as an intermediate in tropospheric organic oxidations. It is commonly referred to as an «-hydroxy radical. These types of radicals react in a

For example, no deuterium isotope effect is observed on the rate constant when CH2OD is substituted for CH2OH (Grotheer et al, 1988; Pagsberg et al, 1989), as would be expected if a direct hydrogen abstraction were occurring.

Similar principles apply to more complex alkenes. One such case is that of isoprene, an important bio-genically produced hydrocarbon:



Figure 6.3 shows some of the major pathways in the

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